U.S. patent application number 15/762178 was filed with the patent office on 2018-10-11 for actuator.
This patent application is currently assigned to THK CO., LTD.. The applicant listed for this patent is THK CO., LTD.. Invention is credited to Kenichi Hasebe, Kazuto Homma, Kaoru Hoshide, Toshihisa Maeda, Nobuyuki Maki, Junichi Sakai.
Application Number | 20180291999 15/762178 |
Document ID | / |
Family ID | 58261927 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180291999 |
Kind Code |
A1 |
Homma; Kazuto ; et
al. |
October 11, 2018 |
ACTUATOR
Abstract
An actuator includes a track member provided with a base
extending along a longitudinal direction and a pair of walls
erected from opposite ends of the base in a width direction, with
rolling-element rolling grooves formed along the longitudinal
direction; and a moving member assembled movably along the
longitudinal direction between the walls, with respective load
rolling-element rolling grooves corresponding to the
rolling-element rolling grooves being formed in the moving members;
and a screw shaft passed through a through-hole formed in the
moving member, with a screw rolling-element rolling groove formed
in the screw shaft, the screw rolling-element rolling groove being
spiral in shape, wherein the moving member has the nut member
attached to the through-hole, with the screw load rolling-element
rolling groove corresponding to the screw rolling-element rolling
groove formed in the nut, the nut member is assembled via a flange
member which includes a lubricant supply device.
Inventors: |
Homma; Kazuto; (Tokyo,
JP) ; Hasebe; Kenichi; (Tokyo, JP) ; Maeda;
Toshihisa; (Tokyo, JP) ; Sakai; Junichi;
(Tokyo, JP) ; Maki; Nobuyuki; (Tokyo, JP) ;
Hoshide; Kaoru; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THK CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
THK CO., LTD.
Tokyo
JP
|
Family ID: |
58261927 |
Appl. No.: |
15/762178 |
Filed: |
September 9, 2016 |
PCT Filed: |
September 9, 2016 |
PCT NO: |
PCT/JP2016/076589 |
371 Date: |
March 22, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16C 29/0623 20130101;
F16C 31/04 20130101; F16C 2322/39 20130101; F16H 25/2204 20130101;
F16C 29/0609 20130101; F16H 57/0497 20130101; F16C 29/084
20130101 |
International
Class: |
F16H 57/04 20060101
F16H057/04; F16H 25/22 20060101 F16H025/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2015 |
JP |
2015-199637 |
Claims
1. An actuator comprising: a track member provided with a base
extending along a longitudinal direction and a pair of walls
erected from opposite ends of the base in a width direction, with a
rolling-element rolling groove formed along the longitudinal
direction; a moving member assembled movably along the longitudinal
direction between the walls, with a load rolling-element rolling
groove corresponding to the rolling-element rolling groove formed
in the moving member; and a screw shaft passed through a
through-hole formed in the moving member, with a screw
rolling-element rolling groove formed in the screw shaft, the screw
rolling-element rolling groove being spiral in shape, wherein the
moving member has a nut member attached to the through-hole, with a
screw load rolling-element rolling groove corresponding to the
screw rolling-element rolling groove formed in the nut, a flange
member is assembled onto the nut member, and the flange member is
assembled onto one end of the moving member in the longitudinal
direction and provided with a lubricant supply device adapted to
supply a lubricant to between the rolling-element rolling groove
and the load rolling-element rolling groove and to the screw
rolling-element rolling groove.
2. The actuator according to claim 1, wherein the lubricant supply
device is placed substantially concentrically with an outer
circumference of the nut member, being formed into an annular shape
having an opening.
3. The actuator according to claim 2, wherein: in the lubricant
supply device, a pair of first supply ports used to supply the
lubricant to between the rolling-element rolling groove and the
load rolling-element rolling groove and a pair of second supply
ports used to supply the lubricant to the screw rolling-element
rolling groove are formed in end portions which face each other
forming the opening; and the first supply ports and the second
supply ports are placed axisymmetrically to each other with respect
to a symmetry axis extending in a radial direction of the lubricant
supply device, and a lubricant introduction portion adapted to
replenish the lubricant is formed on the symmetry axis.
4. The actuator according to claim 1, wherein: a guide member with
the load rolling-element rolling groove formed therein is attached
to the moving member; a rolling groove component with the
rolling-element rolling groove formed therein is attached to the
walls; and at least the guide member, the rolling groove component,
the screw shaft, and the nut member are formed of steel and at
least the track member, the moving member, and the flange member
are formed of a material lighter than the steel.
5. The actuator according to claim 2, wherein: a guide member with
the load rolling-element rolling groove formed therein is attached
to the moving member; a rolling groove component with the
rolling-element rolling groove formed therein is attached to the
walls; and at least the guide member, the rolling groove component,
the screw shaft, and the nut member are formed of steel and at
least the track member, the moving member, and the flange member
are formed of a material lighter than the steel.
6. The actuator according to claim 3, wherein: a guide member with
the load rolling-element rolling groove formed therein is attached
to the moving member; a rolling groove component with the
rolling-element rolling groove formed therein is attached to the
walls; and at least the guide member, the rolling groove component,
the screw shaft, and the nut member are formed of steel and at
least the track member, the moving member, and the flange member
are formed of a material lighter than the steel.
Description
TECHNICAL FIELD
[0001] The present invention relates to an actuator, and more
particularly, to an actuator which can reduce overall weight
without greatly reducing basic performance and can supply grease to
both a rectilinear guide unit and nut member at the same time using
a simple and easy structure.
BACKGROUND ART
[0002] Conventionally, an actuator is known which includes a track
member provided with a base extending along a longitudinal
direction and a pair of walls erected from opposite ends of the
base in a width direction, with a rolling-element rolling groove
formed along the longitudinal direction; a moving member assembled
movably along the longitudinal direction between the walls, with a
load rolling-element rolling groove corresponding to the
rolling-element rolling groove formed in the moving member; and a
screw shaft passed through a through-hole formed in the moving
member, with a screw rolling-element rolling groove formed in the
screw shaft, the screw rolling-element rolling groove being spiral
in shape.
[0003] In such an actuator, rolling elements are interposed,
respectively, between the track member and the moving member and
between the screw shaft and a nut member attached to the moving
member, forming a greasing structure for smooth rolling of the
rolling elements.
[0004] Various types of such greasing structures are known,
including a structure described, for example, in Patent Literature
1, in which a first passage leading to a thread groove of a nut
member is formed to pass a lubricant injected through an inlet for
use to supply the lubricant to a moving member; and the first
passage includes a second passage continuous with the inlet formed
in the moving member, a third passage formed in the nut member, a
fourth passage formed between the moving member and the nut member,
and a fifth passage adapted to supply the lubricant to a rolling
element between a track member and the moving member by being
communicated with the fourth passage.
[0005] Structures such as described above allow the lubricant
supplied through the inlet to be supplied directly to the rolling
element between the track member and moving member as well as the
rolling element between the screw shaft and nut member, making it
possible to supply the lubricant stably.
CITATION LIST
Patent Literature
[0006] Patent Literature 1: Japanese Patent Laid-Open No.
2013-145037
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0007] However, to form plural passages in the moving member and
nut member as described in Patent Literature 1, complicated
processes are needed for machining of the moving member and nut
member, posing a problem in that the machining takes time and
labor, making it difficult to curb production costs.
[0008] Besides, a structure is also known in which greasing
mechanisms are provided to supply a lubricant to a rolling element
between a track member and moving member and to a rolling element
between a screw shaft and nut member, respectively, but the
structure poses a problem in that separate greasing mechanisms are
needed, complicating lubricant supply work.
[0009] The present invention has been made to solve the above
problems and has an object to provide an actuator which can easily
supply a lubricant to each of a rolling element between a track
member and moving member and a rolling element between a screw
shaft and nut member, and can be produced inexpensively by curbing
production costs.
Means for Solving the Problems
[0010] The present invention provides an actuator comprising: a
track member provided with a base extending along a longitudinal
direction and a pair of walls erected from opposite ends of the
base in a width direction, with a rolling-element rolling groove
formed along the longitudinal direction; a moving member assembled
movably along the longitudinal direction between the walls, with a
load rolling-element rolling groove corresponding to the
rolling-element rolling groove formed in the moving member; and a
screw shaft passed through a through-hole formed in the moving
member, with a screw rolling-element rolling groove formed in the
screw shaft, the screw rolling-element rolling groove being spiral
in shape, wherein the moving member has a nut member attached to
the through-hole, with a screw load rolling-element rolling groove
corresponding to the screw rolling-element rolling groove formed in
the nut, the nut member is assembled via a flange member assembled
onto one end of the moving member in the longitudinal direction,
and the flange member includes a lubricant supply device adapted to
supply a lubricant to between the rolling-element rolling groove
and the load rolling-element rolling groove and to the screw
rolling-element rolling groove.
Effect of the Invention
[0011] Since the flange member includes the lubricant supply device
adapted to supply a lubricant to between the rolling-element
rolling groove and the load rolling-element rolling groove and to
the screw rolling-element rolling groove, the present invention can
easily supply the lubricant to each site and produce the actuator
inexpensively by curbing the number of parts without complex
machining.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of an actuator according to an
embodiment of the present invention.
[0013] FIG. 2 is an exploded view of the actuator according to the
embodiment of the present invention.
[0014] FIG. 3 is a sectional view taken along line A-A in FIG.
2.
[0015] FIG. 4 is an exploded view for explaining a configuration of
a moving member used for the actuator according to the embodiment
of the present invention.
[0016] FIG. 5 is a perspective view for explaining a configuration
of a lubricant supply device used for the actuator according to the
embodiment of the present invention.
[0017] FIG. 6 is a partially enlarged view for explaining a
configuration of a lubricant supply device used for the actuator
according to the embodiment of the present invention.
MODE FOR CARRYING OUT THE INVENTION
[0018] An embodiment of an actuator according to the present
invention will be described below with reference to the drawings.
Note that the embodiment described below is not intended to limit
the claimed invention and that a combination of all the features
described in the embodiment is not necessarily essential for the
solution of the present invention.
[0019] FIG. 1 is a perspective view of an actuator according to an
embodiment of the present invention, FIG. 2 is an exploded view of
the actuator according to the embodiment of the present invention,
FIG. 3 is a sectional view taken along line A-A in FIG. 2, FIG. 4
is an exploded view for explaining a configuration of a moving
member used for the actuator according to the embodiment of the
present invention, FIG. 5 is a perspective view for explaining a
configuration of a lubricant supply device used for the actuator
according to the embodiment of the present invention, and FIG. 6 is
a partially enlarged view for explaining a configuration of a
lubricant supply device used for the actuator according to the
embodiment of the present invention.
[0020] As shown in FIG. 1, the actuator 1 according to the present
embodiment includes a track member 10 extending along a
longitudinal direction, and a moving member 20 assembled movably in
the longitudinal direction along the track member 10. Also, a cover
2 is attached to an upper face of the track member 10 to prevent
foreign matter from getting inside the actuator 1. Note that the
moving member 20 extends outside through a gap formed between the
track member 10 and cover 2 and is attached to an object to be
guided.
[0021] As shown in FIG. 2, the track member 10 includes a base 11
extending along the longitudinal direction and a pair of walls 12
erected from opposite ends of the base 11 in a width direction.
Rolling groove components 17 are attached, respectively, to
opposing faces of the walls 12 along the longitudinal direction.
Rolling-element rolling grooves 16 are formed in the rolling groove
components 17, running along the longitudinal direction.
[0022] Also, the track member 10 has a drive member 14 attached and
a drive member mount portion 15 formed at one end in the
longitudinal direction, where the drive member mount portion 15
rotatably supports a screw shaft 30 imparted with a turning force
by the drive member 14. An end wall 13 adapted to rotatably support
the screw shaft 30 described later is formed at another end in the
longitudinal direction. Note that preferably an electric motor or
the like is used as the drive member 14. Note that the rolling
groove components 17 are made of hard metal such as steel and
preferably the track member 10 is made of a material, such as an
aluminum alloy, lighter than steel.
[0023] The moving member 20 is assembled movably along the
longitudinal direction between the walls 12 formed on the track
member 10. A through-hole 21 is formed in the moving member 20 to
allow passage of the screw shaft 30 rotatably assembled on the
track member 10, and a nut member 22 to be screwed onto the screw
shaft 30 is assembled onto the through-hole 21 via a flange member
23.
[0024] Also, as shown in FIG. 3, the moving member 20 includes
guide members 24 assembled such that rolling elements 26 rolling
along the rolling-element rolling grooves 16 formed in the rolling
groove components 17 assembled on the track member 10 will
circulate endlessly. A pair of the guide members 24 contoured to
fit the walls 12 are mounted in a width direction of the moving
member 20 by being fixed to mounting surfaces 20a formed on the
moving member 20. Furthermore, one of the guide members 24 is
attached to the moving member 20 via a biasing member 40. Note that
each of the guide members 24 include a load rolling-element rolling
groove 24a opposed to the rolling-element rolling groove 16, a
rolling-element return passage 29a formed as a through-hole in
parallel to the load rolling-element rolling groove 24a, and a
direction change path 29b configured to couple together a
rolling-element rolling path and rolling-element return path 29a,
the rolling-element rolling path being made up of the
rolling-element rolling groove 16 and load rolling-element rolling
groove 24a, and that when the rolling element 26 is rolling along
the rolling-element rolling path by applying a load to the
rolling-element rolling path, upon reaching one end of the
rolling-element rolling path, the rolling element 26 is passed
through the rolling-element return path 29a via the direction
change path 29b, and is thereby returned to another end. In this
way, the guide members 24 realize endless circulation of the
rolling elements 26.
[0025] Preferably, the biasing member 40 is made of an elastic body
such as a rubber tube, and more preferably, a hollow rubber tube.
The biasing member 40 biases the guide member 24 toward the wall 12
by elastic force. The biasing force has been adjusted such that an
appropriately gap will be provided between the rolling-element
rolling groove 16 and load rolling-element rolling groove 24a
according to a diameter of the rolling element 26 rolling between
the grooves, and thus the gap can be adjusted easily.
[0026] The guide member 24 is fixed by a fastening device 25 such
as a bolt from a direction (e.g., an upper face of the moving
member 20) intersecting a biasing direction of the biasing member
40 of the moving member 20. In this way, since the guide member 24
is fixed to the moving member 20 by the fastening device 25 from
the direction intersecting the biasing direction of the biasing
member 40, the guide member 24 can be fixed by being positioned by
the above-mentioned biasing member 40 without a fastening force of
the fastening device 25 affecting the biasing force of the biasing
member 40. Note that the guide members 24 are made of hard metal
such as steel and preferably the moving member 20 is made of a
material, such as an aluminum alloy, lighter than steel.
[0027] As shown in FIG. 4, the nut member 22 is inserted in the
through-hole 21 formed in the moving member 20, and the flange
member 23 attached to one end of the nut member 22 is fastened and
fixed to one end of the moving member 20.
[0028] A lubricant supply device 60 is attached to that surface of
the flange member 23 which is opposed to the moving member 20.
Regarding the lubricant supply device 60, a replenishing port 61a
is provided on a back face of the flange member 23, protruding
outward, and the lubricant can be supplied into the lubricant
supply device 60 through the replenishing port 61a.
[0029] As shown in FIG. 5, the lubricant supply device 60 is placed
substantially concentrically with an outer circumference of the nut
member 22, being formed into an annular shape having an opening 64.
Note that a pair of first supply ports 62 and a pair of second
supply ports 63 are formed in end portions 64a which face each
other forming the opening 64 of the lubricant supply device 60,
where the first supply ports 62 are used to supply the lubricant to
between the rolling-element rolling groove 16 and load
rolling-element rolling groove 24a and the second supply ports 63
are used to supply the lubricant to a screw rolling-element rolling
groove 31 formed in the screw shaft 30. Furthermore, the first
supply ports 62 and second supply ports 63 are placed
axisymmetrically to each other with respect to a symmetry axis L
extending in a radial direction of the lubricant supply device 60,
and a lubricant introduction portion 61 adapted to replenish the
lubricant is formed on the symmetry axis L.
[0030] Note that the lubricant introduction portion 61, first
supply port 62, and second supply port 63 are connected with one
another through a supply passage 65. A distance from the lubricant
introduction portion 61 to the first supply port 62 and a distance
from the lubricant introduction portion 61 to the second supply
port 63 are set substantially equal to each other, making it
possible to supply the lubricant equally to between the
rolling-element rolling groove 16 and load rolling-element rolling
groove 24a and to the screw rolling-element rolling groove 31.
[0031] As shown in FIG. 6, each of the first supply ports 62
supplies the lubricant to the rolling element 26 rolling between
the rolling-element rolling groove 16 and load rolling-element
rolling groove 24a, through a supply hole (not shown) formed in the
guide member 24 via a sealing member 66.
[0032] Also, the second supply ports 63 supply the lubricant to the
screw rolling-element rolling groove 31 formed in the screw shaft
30 by being connected directly to the screw rolling-element rolling
groove 31.
[0033] As shown in FIG. 2, the screw shaft 30 and nut 22 make up a
ball screw device. In the ball screw device, the screw shaft 30 is
formed by extending along an axial direction, with the spiral,
screw rolling-element rolling groove being formed at a
predetermined lead on an outer circumferential surface; the nut 22
is formed into a cylindrical shape by being provided with a
through-hole through which the screw shaft 30 is passed, with a
screw load rolling-element rolling groove being formed in an inner
circumferential surface of the through-hole, facing the screw
rolling-element rolling groove 31 formed in the screw shaft 30; and
the screw shaft 30 and nut 22 are screwed together, with plural
ball-screw rolling-element being arranged between the screw
rolling-element rolling groove 31 and screw load rolling-element
rolling groove. Note that the nut 22 is not limited to a
cylindrical shape, and may be formed, for example, into a tubular
shape rectangular or the like in cross section orthogonal to the
axial direction.
[0034] The ball screw device with the above configuration is
configured such that the nut 22 will perform motion along the axial
direction of the screw shaft 30 due to relative rotation of the
screw shaft 30 and nut 22. In the motion guide apparatus 1
according to the present embodiment, rotational movement of the
screw shaft 30 rotated by rotation of the drive member 14 is
converted into translatory movement of the nut 22. Note that the
screw shaft 30 and nut 22 are made of hard metal such as steel and
preferably the flange member 23 is made of a material, such as an
aluminum alloy, lighter than steel.
[0035] In this way, since the nut member 22 is assembled via the
flange member 23 assembled onto one end of the moving member 20 in
the longitudinal direction and the flange member 23 includes the
lubricant supply device 60 adapted to supply the lubricant to
between the rolling-element rolling grooves 16 and load
rolling-element rolling grooves 24a and to between the screw
rolling-element rolling groove 31 and screw load rolling-element
rolling groove 32, the actuator 1 according to the present
embodiment can supply the lubricant easily to rolling elements in a
so-called linear motion unit between the track member and moving
member and to rolling elements between the screw shaft and nut
member using a simple and easy structure and can be produced
inexpensively by curbing production costs without requiring complex
machining.
[0036] Also, since the lubricant supply device 60 is placed
substantially concentrically with the outer circumference of the
nut member 22, being formed into an annular shape having an opening
64, the actuator 1 according to the present embodiment can form the
lubricant supply device 60 with a simple and easy
configuration.
[0037] Also, in the actuator 1 according to the present embodiment,
the first supply ports 62 used to supply the lubricant to between
the rolling-element rolling grooves 16 and load rolling-element
rolling grooves 24a and the second supply ports 63 used to supply
the lubricant to the screw rolling-element rolling groove 31 are
formed in the end portions 64a facing each other forming the
opening 64, the first supply ports 62 and second supply ports 63
are placed axisymmetrically to each other with respect to the
symmetry axis L extending in the radial direction of the lubricant
supply device 60, and the lubricant introduction portion 61 is
formed on the symmetry axis L. Consequently, the distance from the
lubricant introduction portion 61 to the first supply ports 62 and
the distance from the lubricant introduction portion 61 to the
second supply ports 63 can be set substantially equal to each
other, making it possible to supply the lubricant equally to
between the rolling-element rolling grooves 16 and load
rolling-element rolling grooves 24a and to the screw
rolling-element rolling groove 31.
[0038] Also, in the actuator 1 according to the present embodiment,
the rolling groove components 17 in which the rolling-element
rolling grooves 16 are formed are attached to the walls 12, at
least the rolling groove components 17, guide members 24, and screw
shaft 30 are formed of steel, and the track member 10 and moving
member 20 are formed of a material lighter than steel.
Consequently, a rated load can be secured and weight reduction can
be achieved at the same time.
[0039] Note that the present invention is not limited to the above
embodiment and that various changes can be made without changing
the spirit and scope of the present invention. For example, the
lubricant supply device 60 may be formed of any material, but if
formed of an elastic material such as rubber, the lubricant supply
device 60 can prevent the lubricant passing through the supply
passage 65 from leaking from the flange member 23. It will be
apparent from the description of the appended claims that any form
resulting from such changes or improvements is also included in the
technical scope of the present invention.
REFERENCE NUMERALS
[0040] 1 actuator, 10 track member, 11 base, 12 wall, 16
rolling-element rolling groove, 17 rolling groove component, 20
moving member, 24 guide member, 24a load rolling-element rolling
groove, 25 fastening device, 30 screw shaft, 31 screw
rolling-element rolling groove, 60 lubricant supply device, 61
lubricant introduction portion, 62 first supply port, 63 second
supply port, 64 opening
* * * * *